This invention relates to ice cream machines, and more particularly it is concerned with an ice cream machine adapted to be incorporated in a refrigerator for making ice cream by utilizing a low temperature atmosphere in the refrigerator.
Generally, when ice cream is made by utilizing the low temperature in a refrigerator, it has hitherto been customary to place an ice cream freezer in the refrigeration chamber of the refrigerator and an ice cream mix in the ice cream freezer, the mix cooling while being agitated. In a refrigerator of the so-called direct cooling system in which the refrigeration chamber is formed by metallic plates integral with the evaporator, the agitation vessel for the ice cream mix is brought into contact with the metallic plates to cool the mix. This system permits ice cream to be made relatively quickly because thermal exchange is effected by heat conduction with a relatively high degree of efficiency. On the other hand, a refrigerator of the type in which cold air produced by the evaporator is forcedly circulated through the refrigeration chamber by a fan to effect heat exchange by heat transfer is very low in heat exchange efficiency because the cooling medium is air. It thus takes a refrigerator of this type seven to eight times as long to make ice cream as a refrigerator employing a direct cooling system, so that the former has not been suitable for practical use. An added disadvantage of the former is that the low rate of cooling results in the ice cream made thereby being gross in the crystals of ice and rough in texture.